In the late 1980's, the cost of transporting commodities by rail in the United States was approximately three cents per revenue-ton mile, plus about one dollar per ton as fixed cost. The comparable cost of transportation by motor truck on public highways was approximately eight cents per revenue-ton mile, also plus an additional one dollar per ton as fixed cost.
The carrier's cost is primarily composed of two major direct costs and two major indirect costs. The largest direct cost is labor for the train crew or for the truck driver. In this instance, railroads enjoy about a 50 to 1 advantage over trucks. Trains are capable of enabling five men to transport 10,000 tons of material. On the other hand, a single truck driver can transport only about 25 tons. This is approximately an 80 to 1 benefit relative to labor costs. The second major direct cost is fuel, in which case the railroads can produce three to five times as many revenue-ton miles per gallon or per dollar of fuel as the trucks can produce.
One of the major indirect costs is the investment in the rolling stock. A 10,000 ton load requires at least five locomotives (costing one million dollars each) plus 100 freight cars at approximately forty thousand dollars apiece. This investment amounts to approximately one thousand dollars per ton of capacity. On the other hand, a new truck and trailer for hauling bulk commodities might cost in the range of one hundred thousand dollars for a 25 ton capacity, or about four thousand dollars per ton of capacity. Once again, the railroads show about a 4 to 1 advantage over trucks in this area.
The other major indirect cost is the upkeep o( the roadway. American railroads spend approximately one-half cent per revenue-ton mile for maintenance of way and structures. Trucks running on public roads pay fuel, taxes and registration and use taxes which add up to roughly the same amount.
Based on the foregoing examples, railroads show approximately a 4 to 1 advantage in the cost of rolling equipment, a 4 to 1 advantage in fuel, and a 80 to 1 advantage in operator wages. Based on these numbers, it would seem that railroads should be able to completely dominate the transportation of bulk commodities.
In practice, however, railroads are most suited for hauling very large quantities (e.g. 10,000 tons in a unit train of coal). Whereas, sand, gravel, stone, and other bulk commodities seldom travel in such large quantities to make up a complete maximum train. This means that many shipments must be delayed while waiting for the railroads to assemble less than trainload lots into an economical train. After the material arrives at the destination, it still must be unloaded from the railroad cars and carried to the point of use. In many cases, this involves truck transportation, and in all cases it involves the unloading of railroad cars.
Many systems have been devised for fast unloading of railroad cars. Most of these require expensive facilities costing millions of dollars. Such systems serve to turn the cars upside down or allow the material to be dropped through the track onto conveyer systems. Unfortunately, a large portion of the sand, gravel, and stone moved by railroads travels in open topped gondola cars which must be unloaded by hand or by some type of machinery. Usually, such machinery dips out one bucket at a time and places it on the ground or onto waiting trucks. This is a fairly slow process which also requires a large number of cars to wait while a single machine unloads them at a time.
U.S. Pat. No. 4,958,977, issued on Sept. 25, 1990, entitled "System for the Transport of Bulk Commodities", described an invention which was a predecessor to the present invention. U.S. Pat. No. 4,958,977 describes a continuous gondola car configuration. A tractor-shovel tranverses the length of the train for the purpose of unloading material from the train. Each of the gondola cars in the train is interconnected in an overlapping fashion. A spring-loaded hinged panel covers the gaps between each of the cars. After experimentation, it was found that the hinged panel were unnecessarily complicated and tended to release material through the gaps between the cars. It was determined that a more efficient and effective approach to the overlapping of adjacent gondola cars was necessary.
Various United States patents have shown rather cumbersome methods and apparatus for unloading gondola cars. U.S. Pat. No. 4,099,635, issued on Jul. 11, 1978, to Leonard et al, shows a loader/unloader mechanism that moves along the top edges of adjacent gondola cars. This includes a complex wheeled chassis that engages the top rim of each gondola car. It also includes wheel spanning legs, pivotally mounted to the chassis, which are adapted to span gaps between adjacent cars and support the chassis as it moves along the gaps. A shovel then dips into the gondola cars for loading and unloading.
U.S. Pat. No. 4,128,180, issued on Dec. 5, 1978, to Mellious, shows an apparatus that is adapted for material handling equipment for the purpose of loading and unloading gondola cars. In particular, this invention shows a backhoe that is modified so as to allow the backhoe to travel along the top portions of gondola cars. The modifications of this device comprise the provision of a smooth, solid underplate at the lower extremity of the undercarriage of the material handling equipment item. This underplate extends laterally beyond the undercarriage so as to provide a skid surface upon which the material handling equipment may be supported. Suitable clamps are installed in the outriggers of the material handling equipment for engaging the sidewalls of an open top container. The backhoe/shovel is slowly moved from gondola car to gondola car by a complex procedure.
U.S. Pat. No. 4,723,886, issued on Feb. 9, 1988, to L. E. Frederking, shows another type of apparatus for loading and unloading gondola cars. This device utilizes tracks that extend along the top edge of the gondola car so that a hydraulic excavator may dip into the gondola car so as to extract material. These tracks are adapted to be placed upon the top of an open top railroad car or gondola car. Each of the tracks has a lip at the outer edge which extends downwardly outside the upper surface of the parallel sidewalls of the railroad gondola car so as to prevent the hydraulic excavator from falling off the gondola car when the two tracks are resting on the sidewalls of the gondola car. In this device, as with the previous top-mounted shovel arrangements, a great deal of leverage is required for the loading/unloading operation of these tractor/shovel systems. Many of these devices require external lines so as to fix the devices in place.
Because most railroad shipments are less than a unit train load, their arrival cannot be predicted with any degree of certainty. As a result, loaded cars must frequently wait several days to be unloaded. Because of these and other problems, the average United States railcar makes only about one revenue trip per month, whereas the average truck makes several revenue trips per week, and on short hauls may even make five or six revenue trips per day.
As a result, one of the major indirect advantages of rail transportation is totally eliminated and reversed. That is, rather than having a 4 to 1 advantage in the investment of rolling stock per ton of capacity, under present methods, the railroads suffer at least a 4 to 1 disadvantage in this factor.
The present invention serves to eliminate the major disadvantage of rail transportation by allowing small shipments to be unloaded immediately upon arrival. This enables the whole assembly of locomotive and cars to make a revenue trip every day or even more on very short hauls.
The use of gondola cars having a continuous trough extending throughout the cars would be one solution to the problem. Such a continuous load-carrying car would enable a vehicle to traverse the interior of the train while unloading the train.
U.S. Pat. No. 4,754,710, issued on Jul. 5, 1988, to K. C. Kieres describes a railway car for carrying freight. In particular, this patent describes the use of a continuous railway car having one continuous trough. The trough is supported at each end wall by trucks. The sidewalls are made up of a plurality of side panels. The side panels have overlapping systems to permit relative motion between adjacent panels for maneuvering curves and hills. The floor has a plurality of laterally and longitudinally extending slope sheets. A flexible center sill extends continuously for the entire length of the railway car.
A difficult problem in the construction of a continuous gondola car has been the arrangement of the walls between adjacent gondola cars. Since the gondola cars will traverse curved sections of track, a great deal of flexibility must be built into the walls in the area of connection between adjacent gondola cars. Although the walls must be flexible, they must also be capable of retaining the material within the gondola car configuration. Furthermore, when the aggregate material is severely compacted within the continuous gondola car configuration, this area of connection becomes a more serious concern. Severe compaction of material within the continuous gondola car could lead to the derailing of, or structural damage to, the continuous gondola car. It is very important that these junction walls be designed in a proper manner so as to accommodate the occurrence of severe compaction. Prior art systems have either failed to address this problem, or have adopted inadequate solutions.
U.S. Pat. No. 2,052,867, issued on Sep. 1, 1936, to R. E. Cartzdafner et al., describes one technique of providing a continuous floor in an open top railroad car. When the train is in operation, the floor between adjacent cars is raised into proper position perpendicular to the floor of the individual railroad cars. When it is necessary to unload the car, the floor is lowered so as to create a continuous passageway between adjacent railroad cars. This patent, however, does not attempt to close the gap along the sidewalls of the train.
U.S. Pat. No. 2,839,010, issued Jun. 17, 1958, to H. J. Harbulak, describes an articulated conveyor train. This device provides articulation between adjacent open top cars. In addition, this provides a solution for the problem of traversing the corners. However, and very importantly, the Harbulak patent, does not address the use of a continuous flat surface at the bottom of the cars. The Harbulak patent utilizes a raised junction that incorporates a rather complex spring-tension system. The Harbulak patent would be unsuitable for the passage of a shovel therethrough.
U.S. Pat. No. 2,793,597, issued on May 28, 1957, to W. R. Walters, describes an articulated connection between railway cars. This patent offers a novel approach in which a flat surface is disposed between adjacent sidewalls on railway cars. A slot is formed at the end of the sidewalls of each railway car. A flat plate will fit and slide freely within the slots. This plate extends between the adjacent railway cars. Although this apparatus presents a desirable solution to the problem of material escaping between the adjacent cars, it is particularly inappropriate for use on curves. Although Walters uses a center strip that will flex and yield on sharp turns, such a center strip would not be appropriate where severe compaction occurs. This center strip would require flexing into the material contained within the gondola cars. Under conditions of severe compaction, the material would resist such flexure. As a result, damage to the slots would result, or, the potential for derailment would be great.
It is an object of the present invention to provide a system for the unloading of gondola cars so as to allow such cars to be loaded and unloaded at a remote location.
It is another object of the present invention to provide a continuous gondola car that enables conventional tractor/shovel configurations to be utilized for the unloading and loading of such gondola cars.
It is another object of the present invention to provide a continuous gondola car configuration that allows such gondola cars to be utilized along the sharpest of turns.
It is another object of the present invention to provide a continuous gondola car that uses a junction between adjacent gondola car that minimizes hazards of structural damage or derailment to such gondola cars.
It is still a further object of the present invention to provide a continuous gondola cars configuration that allows rotation between adjacent gondola cars while minimizing material loss.
It is another object of the present invention to provide a loading and unloading gondola car system that enables a tractor/shovel to have sufficient leverage for effective material unloading.
It is another object of the present invention to provide an unloading system that maximizes economies and capacities while minimizing expense, complexity, and capital and labor investment.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.